After performing an anterior- or lateral-approach discectomy and then inserting an intervetebral spacer/cage/bone strut into a disc space, some spine surgeons prefer not to insert a plate onto the outer surface of the bone and then add fixation through the face of the cephalad and caudal vertebral bodies without first checking the relative alignment of the plate to the surrounding anatomy and endplates. Often times, the plate can be considered to be malpositioned when viewed under x-ray. The malpositioning can be attributed to no consistent effective means of ensuring that the plate is aligned to the cage through pure visualization of the plate within the retracted tissue.
Instead, the current standard of care is to penetrate the cephalad and caudal vertebral bodies using temporary fixations pins through a feature of the plate to temporarily secure the plate in what the surgeons approximates to be perpendicular to the disc space and cage. Once the plate is temporarily secured, the surgeon may or may not release retraction and bring in the x-ray equipment (C-ARM) to take a few anterior-posterior x-rays using the best alignment methods they can by eye with again consideration for the patient's alignment on the table and the pathology they are treating. An x-ray that is erroneously taken slightly off axis (z-axis) can give the surgeon a false impression that the plate is aligned in the ideal location, leading to securement of the plate in what is believed to be an ideal spot, even though it may be malpositioned. Conversely, a surgeon may also get a false impression that the plate is not aligned ideally. This occurs when the plate is in the ideal position but the C-arm is off axis.
A malpositioned plate may sometimes cause patient discomfort and clinical issues like dysphasia/dysphonia in the cervical spine, or adjacent level degradation and tissue irritation in all areas of the spine. Additionally, the bio-mechanics of the plate and the surrounding non fused levels may not be preserved if the plate is malpositioned. Malpositioned plates can contribute to higher likelihood of revision operations. In addition, incorrect selection of plates (i.e., excessively long plates) can result in increased revision surgeries . See, for example, Park, J. Bone Joint Surg., 87A, 3, Mar. 2005, 558-563.
US Patent Publication 2012-0078310 (Bernstein) discloses a device and method of application, combining a cervical plate system with a cervical graft (bone or synthetic) for the safe and efficient stabilization of the cervical spine. The application of a plate to the spine for fixation purposes is widely practiced. The present invention is designed to provide predictable, efficient, and safe fixation of the spine. The present invention is minimally invasive for the anatomical characteristics of the cervical bones or vertebrae. The present invention is designed primarily for use in the cervical spine, but can be applied to any level of application in the spinal column, including the thoracic and lumbo-sacral spine.
US Patent Publication 2012-0226319 (Warsaw Orthopedics) discloses Systems, methods and devices for providing stabilization between first and second vertebrae. More particularly, in one form a system includes an implant configured to be positioned in a disc space between the first and second vertebrae and a freestanding plate for engagement with extradiscal surfaces of the first and second vertebrae. The system also includes an insertion instrument with an engaging portion configured to releasably engage with the implant and the plate such that the implant and plate can be positioned together relative to the first and second vertebrae. In one aspect, an angular orientation of the implant relative to the plate is adjustable when the implant and the plate are engaged by the instrument. In this or another aspect, the implant and plate are held in a contiguous relationship when engaged by the instrument.
U.S. Pat. No. 7,648,511 (Spinecore I) discloses Instrumentation for implanting an intervertebral disc replacement device includes a drill guide comprising a shaft having a proximal end and a distal end and a guide member disposed at the distal end of the shaft and operable to engage an insertion plate that maintains first and second members of an intervertebral disc replacement device in registration with one another for insertion into an intervertebral disc space of a spinal column, wherein the guide member includes at least one guide bore operable to align with an area of a vertebral bone of the intervertebral disc space to which one of the first and second members of the intervertebral disc replacement device is to be attached.
US Patent Publication 2010-0070040 (Spinecore II) discloses instrumentation for implanting a cervical disc replacement device includes cervical disc replacement trials for determining the appropriate size of replacement device to be implanted, an insertion plate for maintaining the elements of the replacement device in fixed relation to one another for simultaneous manipulation, an insertion handle for attachment to the insertion plate for manipulation of the elements, an insertion pusher for releasing the insertion handle from the insertion plate, a drill guide that cooperates with the insertion plate to guide the drilling of tap holes for bone screws to be placed through bone screw holes in the flanges of the replacement device, clips that are applied to the flanges after placement of the bone screws to resist screw backout, and a clip applicator for applying the clips to the flanges.